Asymmetrically loadable press for producing panels

ABSTRACT

An asymmetrically loadable press for producing panels of chipboard and the like, comprising a flat, stationary table, and a parallel flat, movable platen which is moved toward the table on hydraulic press cylinders. When the press is loaded asymmetrically, there are uncovered areas on the table and platen at one end of the press, which produce unbalanced resistance against the movable platen. Hydraulic countersupports are provided on laterally opposite sides of the press at said one end thereof, and these are connected between the stationary table and the movable platen to provide resistance exactly matching the resistance that would be exerted by the material to be pressed if such material filled said uncovered areas. The hydraulic countersupports are supplied with effective piston pressure fluid from the press cylinders, and the total effective piston pressure of the countersupports corresponds to the product of the uncovered area multiplied by the desired specific pressure exerted on the material to be pressed, divided by the operating pressure of the hydraulic press device.

United States Patent [191 Hutter 1 Nov. 26, 1974 1 ASYMMETRICALLY LOADABLE PRESS FOR PRODUCING PANELS Wilhelm Hutter, Krefeld, Germany 22 Filed: Dec. 5, 1972 21 Appl.No.:312,300

[75] Inventor:

[30] Foreign Application Priority Data Dec. 6, 1971 Germany 2160340 [52] U.S. Cl 425/338, 100/258 R, 425/406, I 100/195 [51] Int. Cl. B29c 3/00 [58] Field of Search 425/338, 339, 406; 400/258 R, 258 A, 195

[56] I References Cited UNlTED STATES PATENTS 1,532,140 4/1925 Hutchcns 425/338 2,586,474 2/1952 Moore 425/338 X 2,809,542 10/1957 Albers 100/258 R 2,809,543 10/1957 Zeitlin 160/258 R 2,864,127 12/1958 Marti 425/339 3,050,778 8/1962 .lurgeleit 3.315.304 4/1967 Van Elten 425/339 FOREIGN PATENTS OR APPLlCATlONS 54,196 4/1943 Netherlands 100/258 R Primary Examiner-Robert L. Spicer, Jr. Attorney, Agent, or Firm-Herbert E. Kidder [57] ABSTRACT An asymmetrically loadable press for producing panels of chipboard and the like, comprising a flat, stationary table, and a parallel flat, movable platen which is moved toward the table on hydraulic press cylinders. When the press is loaded asymmetrically, there are uncovered areas on'the table and platen at one end of the press, which produce unbalanced resistance against the movable platen. Hydraulic countersupports are provided on laterally opposite sides of the press at said one end thereof, and these are connected between the stationary table and the movable platen to provide resistance exactly matching the resistance that would be exerted by the material to be pressed if such material tilled said uncovered areas. The hydraulic countersupports are supplied with effective piston pressure fluid from the press cylinders, and the total effective piston pressure of the countersupports corresponds to the product or the uncovered area multiplied by the desired specific pressure exerted on the material to be pressed, divided by the operating pressure of the hydraulic press device.

4 Claims, 5 Drawing F igures SHEET 10F 3 PATENTEL IJUV 2 6 I974 SHEET 2 OF 3 Fig. 4 4

ASYMMETRICALLY LOADABLE PRESS FOR PRODUCING PANELS BACKGROUND OF THE INVENTION The present invention pertains to an asymmetrically loadable press for the manufacture of pressed panels, especially of chipboard panels, said press having a platen movable by means of hydraulic press devices, and a stationary table. Such presses may be designated as single level presses, or provision may be made for the arrangement of several press levels between the movable platen of the press and the fixed table.

The material to be pressed, such as chip fleece, is fed into the press or its various press levels by means of a loading device. It is necessary to load such presses exactly symmetrically, which means that thedimensions of the material to be pressed, as viewed from the center of the press, must be the same in all directions. While it is not difficult to feed the material symmetrically with respect to the width of the press, symmetric feeding of the material with respect to the length is difficult where certain loading methods are involved. The term asymmetrically loadable as used herein, refers to a press in which the material to be pressed is not fed symmetrically, i.e., the area in the press not covered by the material to be pressed is larger at one endof the press than at the other end. The area at one end of the press which is not covered by the material to be-pressed, but which should be covered by saidmaterial for symmetric loading of the press, is called the uncovered area in. the following description.

Asymmetric loading of the press occurs, when certain charging methods are employed, especially when articles such as chip board panels of various lengths are to be pressed in a press. If a conventional press is loaded asymmetrically, this entails the disadvantage of a greater deflection occurring in the uncovered area than in the other press areas, with the result that the material being pressed is pressed to an uneven or nonuniform thickness.

The problem underlying the invention is to create a press which can be loaded asymmetrically, and which has the capability of producing panels that are pressed an exact, uniform thickness.

SUMMARY OF THE INVENTION According to the invention, the foregoing problem is solved in that the area remaining uncovered due to asymmetric loading is supportable by hydraulic countersupports comprising pistons and cylinders which are disposed at one end of the press on laterally opposite sides thereof; the said hydraulic countersupports being actuated by the pressure fluid supplied to the hydraulic press device; and the total piston area of the hydraulic countersupports corresponding to the product of uncovered area multiplied by the desired specific pressure applied, divided by the operating pressure of the hydraulic press device.

The specific pressure applied is the pressure per unit area to which the material to be pressed is to be subjected. The operating pressure is the pressure of a pressure medium required for the operation of the hydraulic press device.

The principle of the invention at hand is to create in the zone of the uncovered area an opposing resistance exactly corresponding to the resistance of the material to be pressed, such as the chip fleece. The resistance of the material to be pressed, which is missing from the uncovered area, is simulated'exactly by the hydraulic countersupports proposed by the invention, which is chargeable with the same pressure medium supplied to the hydraulic press device. without the necessity of a costly regulating device for the hydraulic countersupport.

The cylinders of the hydraulic countersupports may be mounted on the movable platen, with the pistons of the hydraulic countersupports attached to the station- -ary table of the press. However, a reversed arrangement is possible also, in which the cylinders of the hydraulic countersupports are mounted on the stationary table. of the press and, correspondingly, the cylinders attached to the movable platen.

It may be provided, in further development of the invention, for the hydraulic countersupports to consist of several juxtaposed cylinders and pistons actuated in pairs, independent of each other, with the pressure fluid of the hydraulic press device. This makes it possible to press panels of various lengths. When the press is loaded asymmetrically with the material to be pressed, panels of various lengths necessitate uncovered areas of different size. The piston-areas of the hydraulic countersupports are then naturally adapted to the uncovered areas of different size;

The following is a detailed description of the preferredembodiments of the invention, with referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a partially sectioned, schematic side view of a press embodying the principles of the invention;

FIG. 2 is a partially cut-away top view of the arrangement shown in FIG. l,.in which the hydraulic lines have been omitted for the sake of clarity;.

FIG. 3 is a view similar to FIG. 1, showing another embodiment of the invention having. an additional pair of cylinders and pistons in the hydraulic countersupports;

FIG. 4 is a top view of the embodiment shown in FIG. 3, the hydraulic lines being omitted for the sake'of clarity; and

FIG. 5 is a schematic of a modified arrangement of the apparatus in FIG. 3, wherein the cylinders of the hydraulic countersupports are mounted on the movable platen of the press and the pistons are attached to the stationary table.

DESCRIPTION OF THE PREFERRED EMBODIMENT The multilevel press shown diagrammatically in side view in FIGS. 1, 3 and 5 has a plate-shaped stationary table 2 fixed to sheet metal frame 1. A movable part 3,

' designed to operate as the press platen, is disposed so as to be movable vertically through hydraulic press devices 4. The hydraulic press devices havecylinders 5 which are mounted on the sheet metal frame 1, and slidable within the cylinders are pistons 6, which are attached to the movable platen 3. The press cylinders S can be supplied, in the direction of arrow A, with a hydraulic pressure fluid via the lines 7, 8 and 9 from a pressure source such as a pump. When this happens, the pistons 6, and with them the platen 3 of the press, move upwardly, and the material located in the press is compressed. In the embodiment shown, there are plate-shaped heating devices and l 1 rigidly attached to the stationary table 2 and to the movable parts 3. Between them, other heating devices 12 are guided loosely. The heating devices can be heated through channels 13a, such as by steam.

The material to be pressed, such as a chip fleece, is fed into the various levels of the'press when the press is opened. Subsequently, the press is closed and the chip fleece is then pressed into chip board panels under the action of pressure and heat.

The reference numeral 13 designates the material introduced to the various press levels. As is evident particularly from FIGS. 2 and 4, the material 13 is introduced asymmetrically, relative to the press center in the longitudinal direction. The longitudinal centerline of the press is indicated by the dash-dotted line 14b. In conformity with the lettering in FIG. 2, the material to be pressed has the length x on the right side of the press as viewed from the press centerline 14b, while the material to be pressed has the length Y on the left side. The length Y is smaller than the length x by the amount Z. Consequently, the uncovered area on the left side of the press due to its being charged asymetrically is of the size B (X-Y), B being the width of the material to be pressed. The uncovered area has the reference symbol 14.

In order to simulate the resistance of the material to be pressed, which is lacking in the uncovered area, there are provided in the zone of the uncovered area 14 laterally opposed countersupports 15 comprising pistons and cylinders. As shown in FIG. 1, the hydraulic countersupports at the end of the press in the zone of the uncovered area have opposed cylinders 16 ridigly attached to the stationary table 2, in which cylinders are guided sliding pistons 17 rigidly attached to the movable platen 3. The cylinders 16 communicate with line 7 through lines 18. Consequently, the pistons 17 can be actuated by the pressure fluid supplied to the hydraulic press devices 4 when a shutoff valve 19 in line 18 is opened. As is evident, a force opposing the pressing force of the hydraulic press devices 4 is exerted by the hydraulic countersupport 15 from the stationary table 2 to the movable platen 3 of the press in the zone of the uncovered area 14. The total effective piston area 17 of the hydraulic countersupport 15, which is the sum of the face areas 20 of the two pistons 17 in the case of the arrangement shown in FIGS. 1 and 2, corresponds to the product of the uncovered area 14 multiplied by the desired specific applied pressure to which the material 13 to be pressed is to be subjected, divided by the operating pressure of the hydraulic press devices 4, namely the pressure of the fluid in lines 7, 8 and 9. As a result, the uncovered area 14 is so supported that the resistance generated by the hydraulic countersupports 15 matches exactly the resistance that would have been exerted by the material to be pressed if the uncovered area 14 had been covered with material 13. This resistance is simulated exactly without the need for a regulating device. In the arrangement shown in FIGS. 3 and 4, the stationary table 2 has two cylinders l6 and 16a mounted on opposite sides thereof at one end, and slidable within said cylinders are guided pistons 17 and 17a, respectively, the bottom ends of which are fixedly connected to the movable platen 3. The function of thecylinders 16 and pistons 17 corresponds to the functions of the arrangement shown in FIGS. 1 and 2. The cylinders 16a are actuated whenever the uncovered area 14 is greater by another increment 14a (FIG. 4). This occurs when panels of shorter lengths are to be pressed in the press. If the uncovered area 14 is enlarged by the size of the area 140, the hydraulic supports 16a and 17a are added by opening the shutoff valve 22. In that case, the effective piston areas of pistons 17 and 17a are so dimensioned that the sum of the effective piston areas corresponds to the product of the sum of the two areas 14 and 14a multiplied by the desired specific applied pressure of the material to be pressed, divided by the operating pressure of the hydraulic press device.

The arrangement shown in FIG. 5 differs from the arrangement in FIG. 3 only in that the cylinders 16' and 16a of the hydraulic countersupports 15 are attached to the movable press platen 3, and the pistons 17' and 17a are attached to the stationary table 2. In this case, the cylinders are supplied with pressure fluid through channels 23 in the pistons. The arrangement shown in FIG. 5 has the advantage over the arrangement in FIG. 3 in that, cylinders 16' and 16a of the hydraulic countersupports 15 are not exposed to steam rising from the steam-heated presses, and therefore are not subject to corrosion.

What we claim is:

1. An asymmetrically loadable press for the manufacture of panels, especially of chipboard panels, said press having a movable platen (3) which is movable by hydraulic press devices (4) actuated by fluid pressure from a pressure source (7), and a stationary table (2), characterized in that said press is adapted to be loaded asymmetrically between said platen (3) and said table (2) with material to be pressed, leaving uncovered areas (14, 14a) on the platen and table at one end of the press; and hydraulic countersupports (15) on laterally opposite sides of the press at said one end thereof, connecting said stationary table and movable platen, said countersupports each comprising cylinders (16, 16a) and pistons (17, 17a); a conduit line (18) conmeeting said hydraulic countersupport cylinders (16) to said pressure source (7 whereby said hydraulic countersupports are actuated with pressure fluid supplied to the hydraulic press devices (4), and said hydraulic countersupports (l5) exerting an equalizing force on said movable platen (3) and stationary table (2) in the direction to oppose closing together of said movable platen and stationary table; the magnitude of said equalizing force being approximately equal to the compressive pressure that would have been exerted by said material if said uncovered areas (14, 14a) were covered, thereby balancing the pressure distribution exerted against said asymmetrically loaded press table and platen.

2. An asymmetrically loadable press according to claim 1, characterized in that the cylinders (16', 16a) of said hydraulic countersupports (15) are mounted on said movable platen (3) and said pistons (17', 17a) of said hydraulic countersupports (15) are attached to said stationary table (2) of the press.

3. An asymmetrically loadable press according to claim 1, characterized in that said cylinders (16, 16a) of said hydraulic countersupports (15) are mounted on said stationary table (2) and said pistons (17, 17a) of the hydraulic countersupports are attached to said stationary table.

4. An asymmetrically loadable press according to claim 1, characterized in that the hydraulic countersupports (15) consist of at least two pairs of juxtaposed cylinders (16, 16a) and pistons (17, 17a) which can be actuated in pairs, independent of each other, with the pressure fluid of said hydraulic press device. 

1. An asymmetrically loadable press for the manufacture of panels, especially of chipboard panels, said press having a movable platen (3) which is movable by hydraulic press devices (4) actuated by fluid pressure from a pressure source (7), and a stationary table (2), characterized in that said press is adapted to be loaded asymmetrically between said platen (3) and said table (2) with material to be pressed, leaving uncovered areas (14, 14a) on the platen and table at one end of the press; and hydraulic countersupports (15) on laterally opposite sides of the press at said one end thereof, connecting said stationary table and movable platen, said countersupports each comprising cylinders (16, 16a) and pistons (17, 17a); a conduit line (18) connecting said hydraulic countersupport cylinders (16) to said pressure source (7), whereby said hydraulic countersupports are actuated with pressure fluid supplied to the hydraulic press devices (4), and said hydraulic countersupports (15) exerting an equalizing force on said movable platen (3) and stationary table (2) in the direction to oppose closing together of said movable platen and stationary table; the magnitude of said equalizing force being approximately equal to the compressive pressure that would have been exerted by said material if said uncovered areas (14, 14a) were covered, thereby balancing the pressure distribution exerted against said asymmetrically loaded press table and platen.
 2. An asymmetrically loadable press according to claim 1, characterized in that the cylinders (16'', 16a'') of said hydraulic countersupports (15) are mounted on said movable platen (3) and said pistons (17'', 17a'') of said hydraulic countersupports (15) are attached to said stationary table (2) of the press.
 3. An asymmetrically loadable press according to claim 1, characterized in that said cylinders (16, 16a) of said hydraulic countersupports (15) are mounted on said stationary table (2) and said pistons (17, 17a) of the hydraulic countersupports are attached to said stationary table.
 4. An asymmetrically loadable press according to claim 1, characterized in that the hydraulic countersupports (15) consist of at least two pairs of juxtaposed cylinders (16, 16a) and pistons (17, 17a) which can be actuated in pairs, independent of each other, with the pressure fluid of said hydraulic press device. 